import 'package:drift/drift.dart';
import 'package:trainhub_flutter/core/utils/id_generator.dart';
import 'package:trainhub_flutter/data/database/app_database.dart';
import 'package:trainhub_flutter/data/database/daos/chat_dao.dart';
import 'package:trainhub_flutter/data/mappers/chat_mapper.dart';
import 'package:trainhub_flutter/domain/entities/chat_session.dart';
import 'package:trainhub_flutter/domain/entities/chat_message.dart';
import 'package:trainhub_flutter/domain/repositories/chat_repository.dart';

class ChatRepositoryImpl implements ChatRepository {
  final ChatDao _dao;

  ChatRepositoryImpl(this._dao);

  @override
  Future<List<ChatSessionEntity>> getAllSessions() async {
    final rows = await _dao.getAllSessions();
    return rows.map(ChatMapper.sessionToEntity).toList();
  }

  @override
  Future<ChatSessionEntity?> getSession(String id) async {
    final row = await _dao.getSession(id);
    return row == null ? null : ChatMapper.sessionToEntity(row);
  }

  @override
  Future<ChatSessionEntity> createSession() async {
    final String id = IdGenerator.generate();
    final String now = DateTime.now().toIso8601String();
    await _dao.insertSession(
      ChatSessionsCompanion.insert(
        id: id,
        title: const Value('New Chat'),
        createdAt: now,
        updatedAt: now,
      ),
    );
    final row = await _dao.getSession(id);
    return ChatMapper.sessionToEntity(row!);
  }

  @override
  Future<void> deleteSession(String id) async {
    await _dao.deleteSession(id);
  }

  @override
  Future<List<ChatMessageEntity>> getMessages(String sessionId) async {
    final rows = await _dao.getMessages(sessionId);
    return rows.map(ChatMapper.messageToEntity).toList();
  }

  @override
  Future<ChatMessageEntity> addMessage({
    required String sessionId,
    required String role,
    required String content,
  }) async {
    final String id = IdGenerator.generate();
    final String now = DateTime.now().toIso8601String();
    await _dao.insertMessage(
      ChatMessagesCompanion.insert(
        id: id,
        sessionId: sessionId,
        role: role,
        content: content,
        createdAt: now,
      ),
    );
    return ChatMessageEntity(
      id: id,
      sessionId: sessionId,
      role: role,
      content: content,
      createdAt: now,
    );
  }

  @override
  Future<void> updateSessionTitle(String sessionId, String title) async {
    await _dao.updateSessionTitle(sessionId, title);
  }
}